Just got my car and driver today and almost pooped myself when a mention of the rx8 made it in... Even though it was only in the backfires...

Copied out of car and driver....

(In response to the Ferrari 458)

"Ferrari has been claiming a world record for "specific output in a nonturbo production engine" in its mid engined V-8 cars since the introduction of the F355, and you guys have been touting it as biblical truth ever since. I'm tired of hearing it. This claim has always been incorrect. The current champ is the Mazda RX-8. With 238 horses from 1308cc, it produces 177.4 horsepower per liter, dwarfing that of the Ferrari. The previous champ was the 90-92 Mazda RX-7. With 160 ponies from the same 1.3 liters it produced 122.3 hp/liter from only 1308cc, making any such claims about previous Ferraris incorrect"
-Brian Sullins
Avondale, Arizona

"Ahem, a world record for nonturbo production piston engines--Ed

---------------

Brain, if you're out there in the RX8 Club here... well played!

And as always, sorry if this is a repost.

 

awesome

 

While it could be argued that this is 'technically correct' according to published specifications of the RENESIS, it is functionally incorrect. In a piston engine the published capacity is a sum of the volumes when pistons are compressed during an engine cycle. That's fine, and it is self evident. In a rotary "as each rotor gives a power stroke per revolution it is therefore the same as a two stroke. So effectively all of the engine's capacity is being used for every rotation of the output shaft (as for a two stroke). Therefore the actual volume used is twice that of a 4 stroke."

Game over, sorry.

 

Nice. People tend not to question the prestigious brands claims, and hail it as fact.

 

Hardly game over.

All you did is solidify that piston engines are wasting half of their capacity. If pistons used all of their capacity, rather than half, maybe they would indeed be beating the rotary in this measurement. But I guess the rotary engine found a way to use all of the capacity while the piston engine still lags behind.

Do you stick a guy in a wheelchair up against Mr Bolt, and then say that Mr Bolt isn't faster because this was a race between people not using their legs? No. Oh, between people not using half their body, Mr Ferrari might be faster, but Bolt still beats them silly. He still IS faster.

We still hold the record.

 

^Agreed, I'll bet there are 2 stroke engines that can beat the Ferrari claim. They just don't make 2 stroke engines for automobiles anymore.

 

actually doubling isn't correct either. Simply put, engine capacity is how much it displaces in 1 turn of the drive/crank/output shaft/eccentric shaft. Typical piston engine realizes full capacity in 1 turn of the crankshaft whereas a rotary requires 3 turns of the eccentric shaft to realize full capacity. many forget that the rotary is essentially internally geared. The "doubling effect" that is often used as the equalizer comes from the historical 4stroke 2stroke equalizer from other arenas because the rotary has many similarities as 2 strokes. So really the 2-rotor rotary of present is either 1.3 or 3.9l depending how you view it. We've had these debates on other RX forums back in the day, believe me.

 

http://auto.howstuffworks.com/question685.htm

http://auto.howstuffworks.com/rotary-engine.htm

 

swept volume is still 1.3L no matter how you slice it

 

Always two sides to it...
That would be exactly why a guy in a wheelchair and bolt wouldn't be compared in the first place
Now, put bolt on the wheelchair (classifying the 13b as a 2.6/3.9 or whatever) and the comparison would make sense.

Who cares who makes the highest hp/l anyways

 

Efficiency!

Wait. Did I just imply that the renesis was efficient?

Well, it uses it's volume more efficiently than 4-stroke piston engines do

Putting Bolt on a wheel chair would be figuring out how to make the rotary a 4-stroke cycle.

I get what you are saying, that this is trying to compare 2 different things. However, it's fact that 4-stroke piston engines only provide power over half of their swept capacity.

...


I was about to say that rotaries provide power over their entire swept capacity, but that isn't accurate. they only provide power over about 1/3rd of their swept capacity. So I guess this gets down to this question (I'm sure someone knows, someone up on the rotary math)

Is the 1.3L calculation A) calculating the entire housing swept space?
Or B) is it calculating only the swept space where power is provided?

 

Road and Track did the same thing and I think someone here in the forums set them straights and the correction made it to the next issue as well. Nice.

 

Interesting read. I guess it depends on whether we're able to truly compare apples to apples with regards to the rotary and piston motors.

 

I always get in fights with S2K owners on this subject. They really are sensitive about their cars lol.

 

Yeah, Honda's big claim is 1HP for every 10 Cubic Centimeters.

The 99 Civic Si I had was a 1.6 and made 160 HP... not bad VTAK! But like the rotary, all the power is in the high revs.

 

umm, the VTEC 2.0 litre in S2000 is definitely more impressive than the Renesis mechanically and efficiency speaking

 

Hard to admit, but I agree.

 

amazing!

 

I never heard of Honda claiming 1 bhp per every cubic centimeter. That would mean they claim almost 2,000 BHP for the roughly 2,000 CC f20 AP1 motor.......


I have never heard them claim this.

I have heard that it makes 2 bhp per cubic inch though. (roughly 60 cubic inches in a liter )

 

Yeah, you're right... I think I meant 1HP for every 10cc

1.6 liter = 1600 cc producing 160HP

Yeah, if this were to hold true, my motorcycle would product 800HP.... 80 is more like it.